When did it become extinct? This cat is thought to have gone extinct around 10,000 years ago, but as with any prehistoric animal, it is impossible to know exactly when it disappeared.

Where did it live? This feline lived in South America.

Saber Tooth Cat—The skull of Smilodon populator clearly shows the enormous canines of this formidable extinct cat. It used these teeth to inflict fatal wounds on some of the large South American herbivorous mammals. (Ross Piper)

Saber Tooth Cat—The South American Smilo-don populator was the largest saber tooth cat as well as one of the largest cats that has ever lived. (Renata Cunha)

Saber Tooth Cat—The skull of Smilodon populator clearly shows the enormous canines of this formidable extinct cat. It used these teeth to inflict fatal wounds on some of the large South American herbivorous mammals. (Ross Piper)

Saber Tooth Cat—The South American Smilo-don populator was the largest saber tooth cat as well as one of the largest cats that has ever lived. (Renata Cunha)

The Smilodon species, often called saber tooth cats, are among the most famous of all prehistoric beasts, and the species described here was the biggest and most powerful of them all. The Latin name of this cat, Smilodon populator, can be translated as the "knife tooth that destroys." Fully grown, S. popula-tor was the same height and length as a large lion, but much heavier. They were around 1.2 m at the shoulder and may have reached 400 kg—heavier than any big cat alive today. Unlike modern big cats, S. populator had a very stubby tail, and it also had very robust and heavily muscled forequarters—an important adaptation for catching and subduing prey. The bones of S. populator's forelimbs were relatively short and quite broad, indicating that they were attached to some very powerful muscles. These worked together with the muscles in the shoulders and back to provide tremendous force. Without doubt, the most impressive feature of S. populator is the massive canine teeth in the upper jaw. They were huge—far bigger than any tooth that has graced the mouth of any cat before or since. These formidable curved fangs were around 20 cm long, and to accommodate them, the mouth could open extraordinarily wide, up to 120 degrees (a modern lion's maximum gape is about 65 degrees).

Why did S. populator have such monstrous canines? We know that this predator stalked the earth at the same time as many species of large herbivorous mammals, but it is very unlikely that S. populator was capable of subduing the adults of the Pleistocene giants: mammoths, mastodons, giant sloths, and the like. However, the young of these giants and a host of other herbivores were well within the predatory abilities of the saber tooth cats, and they represented a feast for any animal that could bring them down. Catching and killing a large herbivore is no mean feat, even for a hugely powerful, 400-kg cat with 20-cm canines.

Exactly how S. populator and the other Smilodon species caught and killed their prey has been a bone of contention for decades, but a look at the remains of these long-dead animals does give us some clues. Their stocky build and their relatively short limbs indicate that they were probably ambush predators. They may have skulked behind bushes and other vegetation and pounced on an unfortunate ungulate when it came within range. This is a plausible ex planation of how they caught their prey, but how did they kill? For some time, it was thought that these cats used their canines to prize apart the prey's vertebrae, but research has shown that their teeth were much too brittle for this. If the jaws were slammed shut on bone, the canines would have shattered, and without its weapons, a saber tooth would have starved to death. It was also suggested that the teeth were used to slice open the soft underbelly of the prey, but again, the risk of contacting bone during the killer bite was too great. It seems that the Smilodon species actually went for the neck. Using the great muscular strength in their forelimbs to keep hold of the victim long enough to deliver the killer bite, they plunged their huge fangs into the soft throat of the prey, severing the important blood vessels and crushing the windpipe. Biting this way, a large fold of the prey's skin was probably taken in to the cat's mouth, some of which may have been torn away as the feline pulled away. In this scenario, the prey died quickly from blood loss and suffocation, and the cat could have dug in to its meal quickly. It is very likely that S. populator fed on the same sized animals that lions and tigers are capable of dispatching today—it's just that it killed in a different way.

As with many of the amazing mammals that became extinct at around the end of the last glaciation, we can never be certain of what led to the demise of these cats. We do know that the habitats in which these animals evolved went through massive changes as the climate went through cyclical periods of cold and warm, but this alone is not enough to explain the disappearance of these felines. It is interesting to note that the spread of humans around the world appears to coincide with the disappearance of these intriguing cats and many other prehistoric, predatory mammals. Perhaps a combination of climate change and hunting by prehistoric humans pushed the populations of the large herbivores to extinction. As their prey dwindled, the Smilodon species, with their very specialized hunting technique, found it increasingly difficult to find sufficient food in the changing landscape. It is amazing to think that our ancestors probably watched the Smilodon species hunting and going about their everyday lives. Even more intriguing is the possibility that our forebears were probably killed and eaten by these impressive cats.

♦ Three species of Smilodon are known: S. populator, S. fatalis, and S. gracilis. The species described here, S. populator, probably evolved from S. gracilis after it reached South America from the north. S. gracilis probably also gave rise to S. fatalis, which is the most well known of these animals as bones from at least 1,200 individuals have been found in the asphalt deposits of Rancho La Brea in Los Angeles (see the "Extinction Insight" in chapter 4).

♦ The asphalt-stained and well-preserved bones of the Rancho La Brea pits tell us a great deal about these animals, including the afflictions and diseases that troubled them. The S. fatalis bones show evidence of infections, healed breakages, muscle damage, osteo-arthritis, and even wounds inflicted by others of their kind. Torn muscles and ligaments show that these cats used enormous force when attacking their prey. These remains give us an unparalleled glimpse of the earth many thousands of years ago (see the "Extinction Insight" in chapter 4).

♦ The Smilodon species and the other saber tooth cats are sometimes mistakenly called "saber tooth tigers." They are cats, no question, but they are not closely related to the tigers we know today.

♦ Some Smilodon bones have been found in situations that have led some scientists to suggest that they were social and hunted in groups. The brains of S. fatalis are very similar in size and structure to similarly sized modern-day cats, and we are very familiar with the complex social behavior of the lions. There is no direct evidence for well-developed social behavior in any Smilodon species, but it is possible that they lived in groups and depended on teamwork to catch their prey.

♦ It was once thought that the Smilodon species had quite a weak bite, but recent research suggests that their bite was probably as powerful as that of the largest modern big cats. They could also probably use their neck muscles to drive their teeth through the tough hides of their prey.

Scimitar Cat—The scimitar cats are another extinct species of felines with large canine teeth. They were large, long-limbed animals, and they probably used their impressive teeth to kill and dismember large herbivorous mammals. (Renata Cunha)